Exhaust hood

The key to designing an exhaust hood or actually a booth is the face
velocity at the inlet. In the case of a booth which is the only way to
get true use of your fan . This would be the size of the open area at
the front of the booth. say it is 2 ft wide and 3 feet high. This is 6
square feet. Laboratory hoods are designed this way and will use a
face velocity of about 100 feet per minute ( speed not volume or
cubic feet per min.) for the 2’ by 3’ booth this would give a fan
requirement of 6 x 100 or 600 cubic feet per min.

I don’t have a guideline velocity for soldering venting and the 100
cfm is somewhat higher than you would really need.

Kitchen stove hoods only use 30 to 60 cfm. and exhaust from the room
rather than just the soldering area. They don’t do a terribly good
job and they don’t really sweep the work area but they are better
than nothing

While a booth design my be confining it also serves another purpose.
By dimming the lighting during soldering work you improve you
perception of the color of the hot work which can improve your
soldering and annealing. Keeping you pickle pot and doing patinaing
in the booth will help you and your tools. Cyanide based plating also
requires a hood and the full laboratory velocity should be used in
this one. Jesse

Grace: I don’t have a system of my own, as I don’t do any intensive
work, just a little now and then, very little exposure. However, I
have seen small squirrel cage blowers attached to a “fishmouth,” a
small acrylic or sheet metal funnel of elliptical shape which can be
set on the bench right at what you are soldering. This might be more
convenient for you and could probably be home made easily enough.
Vent the blower to the outside. The fishmouth usually has a screen
at the neck to keep parts from going out thru the fan.

HTH,
Roy

Grace; I just installed an exhaust hood in my work shop in our
basement and it turned out very well. I fact, it turned out better
that I expected and best of course, it cost me less than $50.00 to
build. I went to a store in my locality, (Home Depot), and got a ready
made hood, I used a funnel type flu, that is used in the floor ducting
used in air conditioning, down to 6 inches, then attached an 8 foot,
flexible, aluminum tube that is used on the back of a clothes dryer. We
had an old type of bathroom window that is split vertically, I
installed the exit to a piece of 1/4 inch plywood that I installed on
the one side of the sliding glass window. On the out side I installed
the piece that is used for the clothes dryer with the little flapper
door. I feel that the most important thing about my system is, I
talked to about 5 or 6 air conditioning people and they all told me to
PUSH out the fumes and NOT to pull them out… So at the throat of the
system, the end closest to you, I installed an in line fan. What I
used was a 6 inch, DAYTON, AC axial fan… Part no. 4WT42, pushing 238
cfm of air. It works very well and only cost me about $50.00

Hello Everyone, I must admit that the discussion regarding exhaust
hoods is getting me just a little confused! My partner and I are
planning to install one in our studio, and have determined by the
formula in the Hoover and Strong catalogue, that we need 60 cfm. The
article indicated air exchanges at the rate of 6 per hour as adequate
for soldering. They also point out that it is important not to have
your head directly over your work, but rather raised to eye level so
you can look at it rather than over it. Nothing is mentioned about
having a booth around the work area. In a discussion with someone from
OSHA several years ago it was emphasized that the use of a booth
would make the exhaust more efficient and was therefore necessary. It
seemed like that might be overkill and thought I would try it first
without the booth. I installed a 110 cfm Nutone bathroom exhaust fan,
and as far as I can tell, it works just fine. Smoke from an
extinguished match goes straight up, and the fan is so quiet (I think
it is about 1.5 sones) that I sometimes forget to shut it off. I
should mention that it is built into a shaft over the work area and
is about 24 inches above the work surface, and I look at it straight
on. I would appreciate any comments or suggestions as I am buying the
fan this week! Regards to everyone that makes Orchid the wonderful
tool that it is, and a VERY special THANK YOU to Hanuman for all of
his hard work in our behalf!

We have installed the kitchen variety hood in our Tucson
Garage/Studio. The largest I could find at Home Depot was ~ 300 CFM
so I placed an auxillary fan in the exit duct. It was also
purchased at Home Depot. I don’t know the resultant total CFM but it
works fine. We do not notice any residual odor in the garage. My
wife is primarily a fabricator and has not used her casting system
that much. However there was no problem during the casting last burn
out cycle.

Regarding swamp cooling in Tucson, it works very well as long as you
are not in the monsoon season. I am a woodworker. My wife and I
curently share the same cooled space and we have noticed that our
tools rust when the rains come. The best option for keeping the rust
off of your mill is to keep it oiled and covered when not in use. We
use an old pillow case. You do not want to trap moisture under the
cover so use a material that will “breathe”. In the next studio
[coming soon] we will use air conditioning. Here in Tucson A/C is the
best option for keeing the studio dry when the rains come. Insulation
is a key factor in keeping the total cost down and I understand you
have an insulated studio which is good.

An inexpensive pedestal for your mill can be found at Harbor Freight.
They are normally used as grinder stands and I have mounted our
grinders and polishers on them as well. I’ve mounted the grinder
pedestal on a round table top [also found at Home Depot] for mobility.
However, you defnitely need to secure your mill to the floor for
obvious reasons.

There are a number of products on the market to seal conrete floors.
Your local paint supply house should be able to help you. Concrete
floors are notoriously hard on the back and legs. I’ve built wood
boxes which my wife stands on when she is grinding/polishing. You may
want to decorate with colored rubber mats.

Good luck from your Tuscon neighbors.

Terry
The other half of Custom Creations by Patricia.